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Re: Extract Integers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg131424] Re: Extract Integers
  • From: Nigel King <nigel.king at cambiumnetworks.com>
  • Date: Sun, 21 Jul 2013 21:40:36 -0400 (EDT)
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Dana,
I am guessing that

Map[{Numerator[#], Denominator[#]} &, Cases[equ, _Rational, Infinity]]
{{1, 2}, {1, 6}, {1, 24}, {1, 120}}

does not suit your purposes

Nigel

On 21 Jul 2013, at 09:23, Dana DeLouis <dana01 at icloud.com> wrote:

Hi.  I've run out of ideas.  Does anyone know the proper way to extract all the integers from the following simplified version of a larger problem I'm working on?

equ=Series[Exp[x],{x,0,5}] //Normal

1+x+x^2/2+x^3/6+x^4/24+x^5/120

When trying to extract all the integers, I understand numbers like 120 are part of Rational[1,120]

equ //FullForm

<< Not shown here >>

I thought looking at all LevelSpec was the solution, but apparently not.

Cases[equ, _Integer, Infinity]
{1,2,3,4,5}

(* Or *)

Position[equ, _Integer, Infinity]
{{1},{3,2,2},{4,2,2},{5,2,2},{6,2,2}}

Extract[equ, %]
{1,2,3,4,5}

Both ways extract from the numerator, but I just can't seem to extract the {2,6,24,120} inside the denominator.
Does anyone know the proper way?
Thanks in advance.  :>~

Dana
Mac & Math 9






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